To investigate the geometrical packing of the atoms in proteins whose structure has been determined by diffraction procedures. To develop methods for describing packing efficiency, to compare this property of macromolecular structures with that found in molecular crystals of appropriate small molecules. To use this packing data to estimate residual entropy in the protein structures with a view to the contribution such terms may make to the problems of protein structure prediction and ligand association. To investigate the likely modes of motion of all or parts of proteins whose structure is known. To estimate the significance of such motions to the structure of these proteins, and especially to their interaction with known or potential ligands. To suggest which motions might be directly tested by appropriate investigation with high resolution magnetic resonance techniques or with neutron inelastic scattering and to carry out such experiments if practical. To develop a series of chemical reagents both mono and bifunctional which can be used to establish the geometry of the protein components of various molecular aggregates and membranes. To test these reagents on multimeric proteins of known structure, and on ribosomes. To investigate, on the basis of this experience, the protein distribution in the membranes of Mycoplasma laidlawii and subsequently the membranes of cells from higher organisms. The intent is to establish position perpendicular to the plane of the membrane (the inside-outside problem) and also to establish nearest neighbors in the plane of the membrane to the extent that this is definable.